Plastic closure caps can be manufactured in different ways, with continuous threads, with a partial or intermittent thread, more often called an interrupted thread, or with spaced hold-down lugs, used in, for example, child resistant safety vials, which may each be used in conjunction with liner retension segments, disposed on the inner surface of the skirt of the closure cap adjacent the undersurface of the cap. The interruped thread may comprise screw threading, interrupted by a plurality of axially extending gaps on the interior wall of the skirt and the lugs may be circumferentially spaced from one another on the inner wall of the skirt of the cap.
Although specialized systems have been proposed for the manufacture of closure caps having interrupted threads or lugs, because of the variance in the material used in the manufacture of such closure caps and the shape and size of the relevant component parts thereof, such systems have not been satisfactory.
One such system, manufactured by D.M.E. Corporation, includes what is usually called a collapsible core, comprising axially extending segments, the outer periphery of each comprising an arc of a circle, held together in assembled circular closure cap manufacturing relation, by a centre pin disposed on the longitudinal central axis of the core, and an outer ring. After the manufacture of the closure cap, the centre pin is moved out of the centre and the ring surrounding the segments, collapses the segments radially inwardly towards the axis, some collapsing further radially inwardly than others, to permit each segment to clear the undercuts of the thread and permit ejection of each closure cap without interference. Subsequently, the segments are repositioned by the longitudinal pin and ring and the cycle is repeated. However, this core is very expensive and its construction inherently limits the depth, or the thickness, of the thread finish to be manufactured on the skirt of the closure cap, particularly, closure caps smaller than .infin.mm. Furthermore, if one of the segments breaks away, the entire core must be replaced thereby increasing substantially the maintenance costs of the system.
It is therefore, an object of this invention to provide an improved system and components therefor, used in manufacturing closure caps having interrupted threads or hold-down lugs, with or without liner retension segments, having improved characteristics, thereby minimizing initial cost and substantially reducing maintenance costs.
It is a further object of this invention to provide such a system having fewer components.
It is a further object of this invention to provide a more efficient system and components thereof, thereby maximizing product output.
It is still a further object of this invention to provide a system useful in manufacturing closure caps of a size less than 28 mm.
It is still a further object of this invention to provide a system suitable for the manufacture of deep closure caps.
It is still a further object of this invention to provide a system, including a core whereby any broken parts of the core can be individually replaced.
Still other objects and advantages of this invention will be realized by those skilled in the art from the following summary of the invention and more detailed description of preferred embodiments thereof.